The invention relates to improvements in a centrifugal rpm governor as disclosed herein and finally claimed. Such a centrifugal rpm governor is already known from the German Auslegeschrift 23 34 729, which discloses an "internal adjustment device" including, as its most important structural part, a counterstop disposed upon the connecting element between the governor lever and the governor rod in the injection pump, the position of the counterstop being adjusted by the force of an adjustment spring. This counterstop comprises a trip lever, which pivots to perform the adjustment control movement. The adjustment spring is stretched between one end of this trip lever and an adjustable support; such spring is provided with a relatively high degree of stiffness in order to obviate spring buckling which might otherwise occur, due to the oblique relationship between contact surfaces at least in one operational position. Because of such embodiment, the useful range of the adjustment device is severely restricted; that is, a stiff adjustment spring can function only during large differential rpm levels between the onset and the cessation of the adjustment control movement. Furthermore, the effective spring tension varies over the path of the adjustment control movement as a result of the variable action of the lever arm on the counterstop.